1. Field of the Invention
This invention relates to a fitted mattress cover that has a stretchable knitted skirt. More particularly, the invention concerns such a fitted mattress cover in which the skirt is knit from elastic yarns and bulked yarns and has a particular elastic stretch in the longitudinal and a particular inelastic stretch in the transverse directions. The cover fits easily, neatly and snugly on mattresses of different thickness.
2. Description of the Prior Art
Fitted mattress covers comprise a flat top panel of substantially inextensible material and a skirt that depends from the periphery of the top panel. In use, the top panel covers the top of surface of the mattress and the skirt covers the sides of the mattress. Mattresses to which the covers are fitted typically have a thickness in the range of about 7 to about 15 inches. As used herein, the term "longitudinal direction" refers to the direction that follows around the long dimension of the sides of a mattress and the term "transverse direction" refers to the direction that is perpendicular to the longitudinal direction and is parallel to the thickness dimension of the mattress.
Known fitted mattress covers have often included skirts having specially constructed corners or an elastic tape attached to the bottom edge of the skirt, to help hold the fitted mattress cover in place. Early embodiments of such fitted mattress covers were described by Anderson et al, U.S. Pat. No. 3,237,175, column 1. May, U.S. Pat. No. 2,942,280, disclosed one such fitted mattress cover having an inwardly sloping skirt made of a cotton fabric commonly used in undergarments, the end and side walls of the skirt being connected at each corner to form progressively tapered corners, and the bottom edge of one end wall containing an elastic tape, the skirt having extensibility primarily in one direction, the transverse direction. Each of these early fitted mattress covers had skirts that lacked substantial elastic retractive power in the longitudinal direction of the skirt, and accordingly seldom provided a neat, snug fit of the cover to the mattress.
More recently, Seago, U.S. Pat. No. 4,985,953, disclosed a fitted mattress cover having a skirt formed of a gathered layer of inelastic material to which a plurality of spaced apart elastic cords were attached in the longitudinal direction parallel to the periphery of the top panel. The skirt is elastic only in a direction parallel to the elastic cords (i.e., in the longitudinal direction of the skirt) and is substantially not stretchable in the transverse direction. Consequently, mattress covers having such skirts generally are not suited for use over the full range of conventional mattress thicknesses.
Various fitted mattress covers having stretchable skirts of stitchbonded fabrics have been suggested. Some such stitchbonded fabric skirts have substantial elastic stretchability and retractive power in the longitudinal direction as well as some stretchability in the transverse direction. The mattress covers with these types of skirts are intended to accommodate the different thicknesses with which mattresses usually are manufactured. For example, Zafiroglu, the present inventor, in U.S. Pat. Nos. 5,187,952 and 5,247,893, discloses a fitted mattress cover having an elastic fitted skirt formed from a stitchbonded fabric comprising a substantially nonbonded fibrous layer in which elastic yarns, such as spandex elastomeric yarns, are stitched to create lanes of different stretchability in the fabric. The skirt material is capable of stretching 190% ad 60% in the longitudinal direction in the first and second lanes, respectively, and 80 to 90% in the transverse direction. The lanes of different stretchability create a striped or banded appearance in the skirt fabric. Williams et al, U.S. Pat. No. 5,127,115, also discloses a mattress cover with a stitchbonded fabric skirt that has an elastic stretch of 60% in the longitudinal direction and an inelastic stretch of about 30% in the transverse direction. Also, Zafiroglu et al, U.S. patent application Ser. No. 08/397,328, filed Mar. 2, 1995, now U.S. Pat. No. 5,636,393, issued Jun. 10, 1997 discloses a fitted mattress cover having another stitchbonded fabric skirt that does not have a banded appearance. The skirt has a stretchability that is greater in the transverse direction than in the longitudinal direction. The total stretchability in the longitudinal direction is 100 to 200%, with less than half of the stretch being recoverable and the total stretchability in the transverse direction is less than 60% with less one-third of the stretch being recoverable. Zafiroglu, U.S. Pat. No. 5,603,132, discloses a fitted mattress cover having still another stitchbonded skirt that does not have a banded appearance. The stitchbonded skirt is stretchable by at least 50% in the longitudinal direction and at least 100% in the transverse direction, with at least 80% of the longitudinal stretch and at least 30% of the transverse stretch being elastically recoverable. Although fitted mattress covers with such stitchbonded fabric skirts have met with some success in the bedding market, further improvements are desired. The present inventor has found that some mattress covers made with skirts of stitchbonded fabrics that incorporate nonwoven layers of substantially non-bonded or non-entangled fibers, sometimes are prone to mechanical failure and to pilling, especially when the covers are laundered. The present inventor also found that mattress covers made with skirts of stitchbonded fabrics that incorporate nonwoven layers of strongly bonded or highly entangled fibers, though stronger and less prone to pilling, usually do not have sufficient transverse stretch to permit use with mattresses of different thicknesses.
The aim of the present invention is to provide a fitted mattress cover having a skirt which stretches in both the longitudinal and transverse directions so that the cover can be fitted neatly and snugly onto mattresses of different thicknesses, retains its desirable characteristics even after several launderings and does not suffer the shortcomings of mattress covers made with skirts of stitchbonded fabrics.